Harris County prosecutors have dropped charges against a former Houston ISD tutor who was arrested Feb. 1 after a loaded 9 mm gun was found in her car in the parking lot of Fondren Middle School.

Charetta Trishaye Kemp, 28, of Hungerford, was charged with possession of a prohibited weapon. Prosecutors dropped the charge because state law prohibiting guns on school premises does not extend to the school parking lot, said Sarah Marie Kinney, spokeswoman at the Harris County District Attorney's Office.

According to the law, "premises" refers to a building or a portion of a building, Kinney said. The term "does not include any public or private driveway, street, sidewalk or walkway, parking lot, parking garage or other parking area," she said.

However, Houston ISD has an "absolute zero tolerance policy" for guns on school property, which includes the school parking lot, school district spokeswoman Denise Cantu said. The law requires a property owner to post a sign in the parking lot stating the prohibition of guns, she said. Anyone in possession of a gun on any school property breaks the district's rules but without a sign does not break the law, Cantu said. She was not certain whether there is such a sign on display at Fondren Middle School.

Kinney said that because "premises" is defined in the law as excluding parking areas, possession of firearms in that area is legal, Kinney said. "They can have any policy they want, but it didn't violate any Texas law," Kinney said.

A 2011 law forbids an employer from prohibiting an employee who is legally authorized to have a firearm or ammunition from storing the firearm in a locked, privately owned vehicle in an employer-provided parking lot.

Although her criminal case is cleared, Kemp will not be returning to the campus in the 6300 block of South Braeswood, a school district official said.

Kemp resigned her position "in lieu of termination" after her arrest, district spokesman Jason Spencer said. "Her resignation was accepted and she is not returning to HISD."

An anonymous tip to school police prompted a search of Kemp's personal vehicle in the parking lot. She acknowledged the firearm was in her car when questioned by police, Spencer said.